// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)

#pragma once

#include <spdlog/details/null_mutex.h>
#include <spdlog/details/synchronous_factory.h>
#include <spdlog/sinks/base_sink.h>

#include <array>
#include <string>
#include <syslog.h>

namespace spdlog {
namespace sinks {
/**
 * Sink that write to syslog using the `syscall()` library call.
 */
template <typename Mutex> class syslog_sink : public base_sink<Mutex> {

public:
  syslog_sink(std::string ident, int syslog_option, int syslog_facility,
              bool enable_formatting)
      : enable_formatting_{enable_formatting},
        syslog_levels_{{/* spdlog::level::trace      */ LOG_DEBUG,
                        /* spdlog::level::debug      */ LOG_DEBUG,
                        /* spdlog::level::info       */ LOG_INFO,
                        /* spdlog::level::warn       */ LOG_WARN,
                        /* spdlog::level::err        */ LOG_ERR,
                        /* spdlog::level::critical   */ LOG_CRIT,
                        /* spdlog::level::off        */ LOG_INFO}},
        ident_{std::move(ident)} {
    // set ident to be program name if empty
    ::openlog(ident_.empty() ? nullptr : ident_.c_str(), syslog_option,
              syslog_facility);
  }

  ~syslog_sink() override { ::closelog(); }

  syslog_sink(const syslog_sink &) = delete;
  syslog_sink &operator=(const syslog_sink &) = delete;

protected:
  void sink_it_(const details::log_msg &msg) override {
    string_view_t payload;
    memory_buf_t formatted;
    if (enable_formatting_) {
      base_sink<Mutex>::formatter_->format(msg, formatted);
      payload = string_view_t(formatted.data(), formatted.size());
    } else {
      payload = msg.payload;
    }

    size_t length = payload.size();
    // limit to max int
    if (length > static_cast<size_t>(std::numeric_limits<int>::max())) {
      length = static_cast<size_t>(std::numeric_limits<int>::max());
    }

    ::syslog(syslog_prio_from_level(msg), "%.*s", static_cast<int>(length),
             payload.data());
  }

  void flush_() override {}
  bool enable_formatting_ = false;

private:
  using levels_array = std::array<int, 7>;
  levels_array syslog_levels_;
  // must store the ident because the man says openlog might use the pointer as
  // is and not a string copy
  const std::string ident_;

  //
  // Simply maps spdlog's log level to syslog priority level.
  //
  int syslog_prio_from_level(const details::log_msg &msg) const {
    return syslog_levels_.at(static_cast<levels_array::size_type>(msg.level));
  }
};

using syslog_sink_mt = syslog_sink<std::mutex>;
using syslog_sink_st = syslog_sink<details::null_mutex>;
} // namespace sinks

// Create and register a syslog logger
template <typename Factory = spdlog::synchronous_factory>
inline std::shared_ptr<logger>
syslog_logger_mt(const std::string &logger_name,
                 const std::string &syslog_ident = "", int syslog_option = 0,
                 int syslog_facility = LOG_USER,
                 bool enable_formatting = false) {
  return Factory::template create<sinks::syslog_sink_mt>(
      logger_name, syslog_ident, syslog_option, syslog_facility,
      enable_formatting);
}

template <typename Factory = spdlog::synchronous_factory>
inline std::shared_ptr<logger>
syslog_logger_st(const std::string &logger_name,
                 const std::string &syslog_ident = "", int syslog_option = 0,
                 int syslog_facility = LOG_USER,
                 bool enable_formatting = false) {
  return Factory::template create<sinks::syslog_sink_st>(
      logger_name, syslog_ident, syslog_option, syslog_facility,
      enable_formatting);
}
} // namespace spdlog
